This invention relates to the field of electrical connecting devices, and more particularly, to connectors used for heavy duty three-phase electric motors.
Many three-phase electric motors, such as those used in locomotive applications, operate at relatively high currents requiring heavy duty power leads. Furthermore, the environments in which these leads are used can be quite extreme, including exposure to high temperature and stresses.
Some three phase motors require connectors. These connectors typically include a male component, or receptacle assembly, which is designed to releasably connect to a female component, or plug, which in turn is connected to a power supply by cables. The receptacle assembly includes a housing which receives a grommet that, in turn, receives the metal tips or pins of the power leads from the motor. The grommet is made of a flexible silicon rubber and includes holes shaped to receive and grip the power leads so that the tips protrude toward the plug. A backing disk is positioned behind the grommet and is retained in place by a backshell which threads onto the housing. The plug also includes a backshell and a housing having a disk which contains female sockets in a spaced array, corresponding to the orientation of the pins in the grommet of the receptacle, and which are connected to the power supply cables. The backshell for the plug is threaded to engage a threaded flange of the receptacle housing.
A disadvantage associated with this construction is that, when the sockets of the plug are inserted over the pins of the receptacle, any misalignment of the pins with respect to the corresponding sockets may result in one or more of the pins contacting the facing surface of the plug grommet and being pushed rearwardly from its seated and protruding position within the receptacle grommet. As a result, such pins do not make an electrical connection with their respective sockets, and upon powering up, severe damage to the motor results. It has been learned that, if the force necessary to push one or more pins rearwardly from its grommet is at least 200 pounds, the likelihood of not making a full connection is significantly reduced.
Accordingly, there exists a need for a receptacle assembly for a three phase motor which insures integrity of electrical connection and is able to withstand temperatures of 125.degree. C.